[U-Boot] [ANN] U-Boot v2020.01-rc4 released

Hey all,

It's release day and here is v2020.01-rc4. Yes, I'm still working on fixing all of the issues that pop up as I get the MTD clean-up series ready to go. In fact, what I need to do at this point is grab the handful of size reduction patches that this has shown are worthwhile, then I can do the MTD series. Then we're down to just fixing up misconversions where things got turned off.

Once again, for a changelog, git log --merges v2020.01-rc3..v2020.01-rc4 and as always, I ask for more details in the PRs people send me so I can put them in the merge commit.

I'm planning on doing -rc5 on December 23rd with the release scheduled on January 6th. Thanks all!